The invention of continuous extrusion has made a great change of traditional processing of non-ferrous metals, it is characterized by cancellation of heating and annealing process, which saves investment, reduces energy consumption, enhances output, simplifies production process, and solves the disadvantage of discontinuous processing and length limitation by traditional process. To continuously and precisely extrude aluminum profiles, it requires clean surface of the aluminum rod and precise control over the feed stock.
Aluminum is characterized by active chemical reaction, the fresh and clean surface of aluminum at room temperature can easily react with oxygen in the air to form an oxide layer. When continuously and precisely extruding aluminum profiles, the stored aluminum component needs to undergo on-line shape finishing and surface cleaning or the same processing off-line with additional protection before the processed aluminum rod can go on-line for subsequent processing.
Conventional methods of surface cleaning treatment of aluminum or its alloy components mainly include chemical cleaning, grinding, rotary peeling, and centrifugal gravity scraping. The chemical method uses alkali or acid to remove stains and oxides from the surface of the aluminum component, and then the lye and acid is rinsed and the aluminum component is dried. The disadvantage of the chemical method is the long processing flow which can easily cause secondary oxidation due to exposure to air and may also raise an environmental issue. The grinding method uses a grinding brush to repeatedly burnish the aluminum component in order to remove stains and oxides from its surface. The disadvantage of the grinding method is that the heat generated by friction induces secondary oxidation on the aluminum surface. The rotary peeling method is dedicatedly designed for aluminum rods, which places several peeling cutter sets along the advancing direction (axial) of the aluminum rod. The three peeling cutters of each set are evenly distributed on the rotary disk which comes with the self-centering mechanism and are tilted with the aluminum rod. All peeling cutter sets fully cover the surface of aluminum rod. The stored aluminum rod firstly goes through the shape finishing, then, goes through continuous peeling by the cutters. The surface of the aluminum rod is fully treated when all of the peeling cutters on the rotary disk and all of the sets are used. The disadvantage of the rotary peeling method is low precision and poor uniformity. The centrifugal gravity scraping method is also designed especially for aluminum rods, similar to the rotary disk structure. When the shape finished aluminum rod passes through the rotary disk, the mechanical structure of the rotary disk, which is affected by centrifugal gravity, drives the peeling tool into contact with the aluminum rod, peeling the surface layer. The disadvantage of this method is that the length of the aluminum rod is limited and less uniformity. The above-mentioned methods are not suitable for on-line surface scraping nor can they satisfy the processing requirement of providing uniformity and consistent treatment of the aluminum rod by high precision extrusion and continuous production.
To avoid the disadvantages of the above-mentioned methods when conducting on-line shape finishing and surface cleaning, there is an urgent need for high precision extrusion and continuous processing the aluminum profiles. To meet the need, one embodiment of the method uses highly precise molds scraping onto the aluminum component to accomplish shape finishing and surface cleaning. The present invention refers to the mold method which satisfies the requirement of providing uniformity and consistent of aluminum rods by precision extrusion and continuous processing of aluminum, aluminum alloy, aluminum bimetallic or multi-metallic composite profiles or special profiles. The method achieves precise control over the molding process and precision extrusion for the continuous production line.